Electrical device with crossover of electrode connecting lines

ABSTRACT

The invention relates to an electrical device comprising a substrate carrying at least one component comprising at least one electrode, a first connecting line electrically connected to said electrode, wherein the first connecting line bridges a second connecting line by means of a crossover. The crossover is, at least at one side, bounded by an electrically insulating structure. The invention allows new testing methods and efficient lead-outs for an electrical device, such as electroluminescent display devices.

The invention relates to an electrical device comprising a substratecarrying at least one component comprising at least one electrode, afirst connecting line for electrically connecting to said electrode,wherein said first connecting line bridges a second connecting line bymeans of a crossover.

U.S. Pat. No. 5,936,344 discloses an electroluminescent elementcomprising a substrate carrying organic light-emitting devices, eachhaving a plurality of organic material layers made of organic compoundssandwiched between an anode layer and a cathode layer. The substratefurther carries a conductive connecting line for electrically connectingan anode or a cathode to a bonding pad at the periphery of the displaypanel. The connecting line is made of the same material as the cathodein a standard cathode-making process and has a thickness substantiallythe same as that of the cathode. The electroluminescent element hasconnecting lines at the level of the anode layer and the level of thecathode layer. A connecting line at the level of the anode layer may beconnected with a connecting line at the level of the cathode layerthrough openings. By using such structures, crossovers of connectinglines can be obtained. A crossover of a connecting line is anelectrically insulating structure for bridging one connecting line withanother connecting line without making electrical contact between thesetwo connecting lines. Such crossovers can be used for connecting theanode and the cathode of each electroluminescent element to theappropriate bonding pad, or for re-routing the connecting lines of anelectrical device or an integrated circuit, such as a chip on glass.

A disadvantage of the prior art is that the process of manufacturingelectroluminescent elements or integrated circuits is not suitable tomeet the trend towards high resolution, which results in a substantialscale down of the electrode pitch. A considerable number of thehigh-resolution electroluminescent elements produced had a short-circuitbetween two adjacent connecting lines when the standard cathode-makingprocess was used for simultaneously forming cathodes, connecting linesand crossovers.

The invention aims, inter alia, to provide an electrical device whichhas a reduced risk of a short-circuit between adjacent connecting linesand/or crossovers. Such an electrical device may be anelectroluminescent display device or an integrated circuit whereinadjacent connecting lines are involved. For an electroluminescentdisplay device, preferably, the use of the standard cathode-makingprocess for simultaneously forming cathodes, connecting lines andcrossovers is permitted.

This aim is achieved by providing an electrical device characterised inthat the crossover is, at least at one side, bounded by an electricallyinsulating structure. The structure accurately delimits the crossoverand electrically separates the crossover on one side of the structurefrom the area on the other side of the structure. It was found that thenumber of high-resolution display panels according to the invention thathad an electrical short-circuit between two adjacent connecting lines,decreased dramatically. This result was obtained even when the standardcathode-making process for simultaneously forming cathodes, connectinglines and crossovers was applied.

The structures can be aligned very accurately and can be used to makecrossover lines close to each other. For example, on each side of astructure, a crossover can be established, yielding a high density ofcrossovers and connecting-lines which is necessary for high resolutiondisplay panels. Moreover, the structure permits the use of the standardcathode-making process for simultaneously forming cathodes, connectinglines and crossovers.

The use of electrically insulating structures for the structuring of thecathode of an organic electroluminescent display panel is known from forexample U.S. Pat. Nos. 5,294,869, 5,701,055, and 5,962,970. The rampartsdivide the metal layer deposited so that the metal layer on the one sideof the rampart is formed electrically separate from the metal layer onthe other side of the rampart. None of the publications howeverdiscloses the use of electrically insulating structures to define anarea of a crossover for connecting lines.

It is further preferred that the material between the conductiveconnecting line and the further conductive connecting line, at theposition of the crossover, is an electrically insulatingnon-electroluminescent material, preferably an electrically insulatingorganic material, such as a resist. SiO_(x) or SiN_(x) deposited byPECVD may be used as well. It should be noted that, in contrast with theprior art, the electrically insulating structures in accordance with theinvention may be formed on top of the electrically insulatingnon-electroluminescent material which electrically isolates thecrossover to be formed from the underlying structures, such as furtherconnecting lines or light emitting devices.

Preferably, the electrically insulating structures used for bounding acrossover according to the invention have an overhanging portionprojecting in a direction parallel to the surface of the substrate. Morepreferably, the structures according to the invention have aninverse-tapered or T-shaped cross-section. By using such structures,bent or meandering connecting lines can be formed since electricalseparation of the electrically conducting layer on top of the structuresis obtained.

Preferably, each crossover is surrounded, preferably completely, by aseparate electrically insulating structure, which reduces the risk of ashort-circuit even further, because, in this case, there are twoseparate structures in-between two adjacent crossovers.

The electrical device may be an electroluminescent display devicecomprising several display pixels. A display pixel comprises a firstelectrode or set of electrodes and a second electrode or set ofelectrodes with an electroluminescent material layer sandwiched betweenthese electrodes. The first or second electrodes may be connected to thefirst connecting line. The way of electrically connecting the first orsecond electrodes to their respective connecting points is particularlyuseful in organic electroluminescent display panels because themanufacturing methods used for making such organic electroluminescentdisplay panels are particularly suited and sometimes already adopted formaking the structures and for using the standard cathode-making processfor forming cathodes, connecting lines and crossovers in one step.

Alternatively the electrical device relates to an integrated circuitemployed on a glass substrate comprising connecting lines for theintegrated circuit.

The invention further relates to a method for manufacturing anelectrical device comprising a crossover of at least a first connectingline over at least a second connecting line, at least one of saidconnecting lines connecting to an electrical device, comprising thesteps of:

-   -   Forming, either simultaneously or successively, said first        connecting line and said second connecting line for said device        on a substrate;    -   depositing an insulating layer on or over said first connecting        line and said second connecting line, at least at the positions        where said crossover is to be formed,    -   defining or creating openings in said insulating layer at        positions where electrical contacts are to be provided with said        first connecting line and a connection point,    -   forming electrically insulating structures which, at least        partially, bound the area where said crossover is to be formed,    -   depositing an electrically conductive layer to connect said        first connecting line to said connecting point, which connecting        point may be connected to another, second connecting line.

Preferably the electrically insulating structure surrounds thecrossover. It is possible then to apply the electrically insulatingstructures before the insulating layer is deposited. The insulatinglayer may then be deposited only in the region where the crossover is tobe formed.

Preferably the method for manufacturing a crossover is applied inconnecting a display panel having a plurality of display pixels.Application of this method for a display panel are particularly usefulin organic electroluminescent display panels, because the manufacturingmethods used for making such organic electroluminescent display panelsare particularly suited and sometimes already adopted for making thestructures and for using the standard cathode-making process forsimultaneously forming cathodes, connecting lines and crossovers.

The invention also relates to a test structure for testing a displaypanel comprising at least a first set of electrodes and a second set ofelectrodes, wherein said test structure is adapted to separately connectto said first set of electrodes and said second set of electrodessimultaneously from a single side of the display panel.

Testing of display panels before any connector and/or driver electronicshas been applied is key to increase the overall yield of successfullymanufactured display device and thus to decrease the manufacturingcosts.

The invention moreover relates to a method for manufacturing teststructures and a method for testing display devices.

The embodiments of the invention will be described in more detail belowwith reference to the attached drawing (not to scale) in which

FIGS. 1A, B schematically illustrate a display device, including theconnections to the display panel and a display pixel;

FIGS. 2A-D illustrate the process of connecting to a display panel shownin FIG. 1A, according to an embodiment of the invention;

FIGS. 3A and B show an enhanced view of a section of FIG. 2D.

FIG. 4 schematically illustrates the use of conventional comb structuresfor testing a display panel.

FIGS. 5A-D show various embodiments of test structures according to anembodiment of the invention.

Next an embodiment of the invention wherein the electrical device is anelectroluminescent display device will be discussed. It should beappreciated that the invention can also be applied for other electricaldevices wherein components thereof are connected via connecting lines,such as integrated circuits, polymer electronics, solid state lasers,and for re-routing of signal lines or other lines on e.g. the electricaldisplay device.

FIGS. 1A and 1B show an electroluminescent display device 1 comprising adisplay panel 2 exhibiting a plurality of display pixels 3 (LEDs) and asingle display pixel 3, respectively. The display pixels 3 are arrangedin a matrix of rows and columns and are mutually connected via firstconnecting lines 4 and second connecting lines 5. The display pixel 3may be connected with further first connecting lines 6 as well.

FIG. 1B shows a schematic cross-section of a LED display pixel 3 havingR, G and B sub-pixels. It should be appreciated that display pixels maybe much more complex in reality; however the illustration in FIG. 1B issuited for the purpose of describing the embodiment according to theinvention.

The display pixel 3 comprises a substrate 7. Preferably, the substrate 7is transparent with respect to the light to be emitted by the displaysub-pixels R, G and B. Suitable substrate materials include syntheticresin which may or may not be flexible, quartz, ceramics and glass.Alternatively a metal substrate with a dielectric layer on top can beapplied for top emission displays. The total thickness of the substratetypically ranges from 50 μm to 10 mm, depending on the application. Forlarge substrates, a larger substrate thickness is usually required.

A first electrode 8, commonly referred to as the anode, is depositedover or on top of the substrate 7. Preferably said first electrode 8 istransparent with respect to the light to be emitted. For example, atransparent hole-injecting electrode material, such as Indium-Tin-Oxide(ITO), is used. Conductive polymers such as a polyaniline (PANI) and apoly-3,4-ethylenedioxythiophene (PEDOT) are also suitable transparenthole-injecting electrode materials. Preferably, a PANI layer has athickness of 50 to 200 nm, and a PEDOT layer has a thickness of 100 to300 nm. If an ITO hole-injecting electrode is used, the first electrodeis preferably the anode.

Next an insulating layer 9 is deposited on or over the first electrode8. Insulating layer 9 is subsequently removed partially, at least at thepositions where the display sub-pixels R, G and B are to be formed. Itis noted that the invention is also applicable for monochrome displays.Next one or more layers 10, comprising luminescent materials, aredeposited on or over the first electrode 8, at least at the positionswhere the sub-pixels R, G and B are to be formed. Although any techniquemay be used to provide the electroluminescent material, if anelectroluminescent material having a high molecular weight is used, thelayer 10 comprising the electroluminescent material is preferablydeposited as a liquid using techniques known in the art, such as inkjetprinting, spin-coating, dip-coating, Langmuir-Blodgett technique,spray-coating, and doctor-blade technique. Alternatively, if anelectroluminescent material having a low molecular weight is used, thelayer 10 comprising the electroluminescent material is preferablydeposited via a gaseous medium using techniques known in the art, suchas vacuum deposition and chemical vapour deposition (CVD).

The layer 10 comprising an electroluminescent material is covered with asecond electrode 11, which layer is at least deposited at the positionswhere a display sub-pixel R, G or B was formed. Second electrode 11 iscommonly referred to as the cathode. When a hole-injecting electrodematerial, such as Indium-Tin-Oxide (ITO), is used for the firstelectrode 8, the second electrode must be an electron-injectingelectrode. Such an electron-injecting electrode is suitably made of ametal (alloy) having a low work function, such as Yb, Ca, Mg:Ag Li:Al,Ba or is a laminate of different layers such as Ba/Al or Ba/Ag. Such asecond electrode is generally deposited by means of vacuum deposition.

The light emitting structure of display pixels 3 may be packaged byapplying an encapsulation layer (not shown) over the entire structure orby means of a glass or metal lid.

The first connecting lines 4 and second connecting lines 5 are locatedoutside the area of the display panel 2. Connecting lines 4, 5 enablesignals to be applied to the displays pixels 3, to either the firstelectrodes 8 or the second electrodes 11. In FIG. 1A these signals mayrelate for a colour display device 1 to the colour signals red (R),green (G) and blue (B). Conveniently the complex of a red, green andblue display sub-pixel is referred to as a display pixel 3. It is notedthat the display sub-pixels R, G and B may be arranged in severalconfigurations to form the display pixel 3, such as a rectangular or atriangular configuration. The display pixels 3 may be mutually connectedto further first connecting lines 6 as well. The invention as describedbelow may also be applied for e.g. routing these lines over the displaydevice 1, e.g. by routing the further connecting lines 6 so as to crossthe second connecting lines 5 and/or the first connecting lines 4.

As discussed above, in present-day display devices a trend toward highresolution exists, which results in a substantial scale down of theelectrode pitch, i.e. the distance between the anodes 8 and/or cathodes11 within or between display pixels 3. As a consequence, at least thedistances between the first connecting lines 4, connecting to theseelectrodes of the display pixels, decrease in accordance with thistrend. Therefore the probability of electrical short-circuits betweenadjacent first connecting lines 4 increases, especially if the standardcathode-making process is used. In the standard cathode-making process,the cathodes 11, first connecting lines 4 and crossovers of the firstconnecting lines 4 over the second connecting lines 5 or furtherconnecting lines 6 are made simultaneously

Focussing now on the area 12 of the display device 1 in FIG. 1A, whereinthe connecting lines 4 and 5 meet, it can be observed that some of thefirst connecting lines 4 are connected to a connecting point 13 that maybe connected to one of the second connecting lines 5, providing a signalfor the R sub-pixel, while others of the first connecting lines 4 haveto cross the second connecting lines 5 by means of a crossover 14 inorder to connect to another connecting point 13 at one of the secondconnecting lines 5, such as the ones providing signals for the G or Bsub-pixels. It will be appreciated that said connecting points 13 do notnecessarily connect to a second connecting line 5 supplying signals;they may alternatively be bonding pads or any other connecting points.

FIGS. 2A to 2D show a method according to the invention for the area 12of FIG. 1A. Cross-sections X-X and Y-Y as indicated in the top view,showing only the intersected areas, are displayed as well.

In FIG. 2A the first connecting lines 4 and the second connecting lines5 are deposited on the substrate 7 of the display device 1 in athickness of e.g. 150 nm. Said first connecting line 4 is typically madefrom a material having a low electric resistivity, such as a metal or analloy. Preferably, the connecting lines 4 and 5 are made from the samematerial as the first electrode 8. In this case, the first electrode 8and the connecting lines 4 and 5 can be formed simultaneously on thesubstrate 7. For example, Indium-Tin-Oxide (ITO) may be used for boththe connecting lines 4 and 5 and the first electrode 8. Alternatively,the connecting lines 4 and 5 are made from an ITO layer on top of thesubstrate, which ITO layer is covered by a layer of a material having alow electric resistivity, such as a metal or an alloy. The connectinglines 4 and 5 and the first electrode 8 may be formed by conventionaldeposition methods, such as vacuum deposition, and patterning methods,such as photolithography.

In FIG. 2B the deposition of an insulating layer 15 on or over theconnecting lines 4, 5 and the substrate 7 is illustrated. The insulatinglayer 15, having a thickness of e.g. 2 μm for a photoresist, is at leastapplied where the crossovers 14 are to be formed, but may be applied inadjacent areas as well. The insulating layer 15 is preferably obtainedfrom a conventional photoresist and planarises the substrate 7. It isnoted that the insulating layer 15 and the insulating layer 9 in thedisplay panel 2 may be the same layer deposited in a single processstep. Openings 16, i.e. via's in the insulating layer 15 to the firstconnecting lines 4 and second connecting lines 5, are defined or createdin the insulating layer 15, e.g. by photolithography or laser ablation.

In FIG. 2C electrically insulating structures 17 are applied on top ofthe insulating layer 15. The structure 17 accurately delimits, at leastpartially, the boundary where a crossover 14 is to be formed and thus,at least partially, the outline of the crossover 14. Although anypatterning technique may be used to provide the structures, saidstructures are preferably obtained by photolithographically patterning aconventional photoresist. A suitable width is 1 to 50 μm, or, preferably10 to 20 μm, a suitable height is 0.5 to 30 μm, a preferable height is 2to 6 μm. The transverse profile of the structure 17 is suitablyrectangular, although a structure 17 having an overhanging portionprojecting in a direction parallel to the surface of the substrate ispreferred.

In addition, crossovers 14 can be formed by surrounding them withstructures 17 having an overhanging portion projecting in a directionparallel to the surface of the substrate. This is more clearlyillustrated in FIG. 3, which is discussed below.

Preferably, each crossover 14 is surrounded by a separate structure 17,as illustrated in FIGS. 2C and 2D. This reduces the risk of ashort-circuit even further, because, in this case, there are twoseparate structures 17 in-between two adjacent crossovers 14. In thiscase, the structure 17 may be formed before the connecting lines 4 and 5are covered by the insulating layer 15. Said covering can now carriedout by done by depositing insulating material onto the area surroundedby the structure, for example by ink-jet printing. Subsequently, saidinsulating material is removed at the positions where openings 16 are tobe formed, for example using laser ablation.

It is advantageous to deposit the layer 10 of the display pixel 3,comprising electroluminescent material, after the formation of thestructures 17, because in this case the electroluminescent layers 10 arenot exposed to the conditions prevailing in the structure-makingprocess, which may be hostile to the electroluminescent materials.

In FIG. 2D an electrically conductive layer 18 is applied on or over thestructure shown in FIG. 2C. The crossovers 14 are formed here since theelectrically conductive layer 18 connects the first connecting lines 4with the second connecting lines 5, as is most clearly illustrated incross-section Y-Y indicated by means of arrows. The electricallyconductive layer is typically made of a material having a low electricresistivity, such as a metal or an alloy and has a thickness preferablybetween 100-500 μm. If the electrically conductive layer 18 is depositedby means of vacuum deposition, which is generally the case, thestructures 17 or a part thereof may conveniently serve as a shadow maskfor the formation of the crossovers 14. When exposed to the materialflux from which the crossovers 14 are deposited in vacuum, thestructures 17 prevent the deposition of electrically conductive materialat the locations which are in the shadow region provided by thedirection of the material flux with respect to the structures 17, thusobtaining patterned crossovers 14 or a patterned electrically conductivelayer 18.

Preferably, the electrically conductive layer 18 providing thecrossovers 14, is of the same material as the second electrode orcathode 11 of the display pixel 3. In this case, the second electrode 11and the electrically conductive layer 18 can be formed simultaneously inone vacuum deposition step.

It was previously noted with respect to FIGS. 2A-D that the drawingswere not to scale. In FIGS. 3A and B a more realistic impression isgiven of the dimensions of the various layers and the shapes of thelayers in the X-X cross-section, indicated by 19 in FIG. 2D and the Y-Ycross-section, indicated by 20 in FIG. 2D, respectively.

The display panel 2 including the connecting lines may be packaged byusing an encapsulation layer (not shown) e.g. if the crossovers 14 areto be permanently applied in the electrical device 1. Alternatively athin film package, comprising organic or inorganic components orcombinations thereof, can be applied for protection. Such a thin-filmpackage may substantially reduce diffusion of water into the structure.If the crossover structure is applied for testing, as will be discussedbelow, the crossovers 14 do not have to be packaged by the encapsulationlayer but may be carefully handled until the test has been performed.

Various aspects of the method of manufacturing crossovers as describedabove can be used advantageously for testing an electrical device suchas the display panel 2. Testing of display panels 2 before anyconnectors and/or driver electronics have been applied is key toincrease the overall yield of successfully manufactured display devicesand thus to decrease the manufacturing costs.

Conventionally two methods can be distinguished in which the appearanceof these short-circuits can be tested. First, all the electrodes 8, 11of the display panel 2 are contacted separately. This type of testinginvolves high expenses, since machine positioning with high accuracy ofthe electrode pitch is needed, and is therefore economicallyunattractive. Secondly, test comb structures 21, 22 can be applied, asshown in FIG. 4. In using these comb structures, each second anode 8 isconnected on one side of the display panel 2 with a first comb structure21 and the other remaining anodes 8 are connected to a second combstructure 21′ at the other side of the display panel 2. The sameprocedure is applied for the cathodes 11.

Three types of short-circuits can be observed in display panels 2.Firstly, defects in the electroluminescent layer 10 may result inshort-circuits between the first electrode or anode 8 and the secondelectrode or cathode 11 (AC-shorts). Secondly, adjacent anodes 8 in thedisplay panel matrix 2 may connect each other, i.e. an A-A short exists.Thirdly, adjacent cathodes 11 may form a C-C short-circuit. By measuringthe resistances using the comb structures 21, 22 the presence ofshort-circuits A-A, C-C and A-C can be detected. The comb-structures 21,22 are removed after testing.

Using these test comb structures is a low-cost alternative, but usingthese comb structures for present-day display panels, being colourdisplays and split or tiled displays and displays with a very smallelectrode pitch, is difficult, if not impossible. For split displaysonly one side of the display is available for connection by a test combstructure. The R, G and B sub-pixels appeared to have different failurecharacteristics, i.e. short-circuit behaviour between the R, G and Bsub-pixels is different. Therefore preferably each colour R, G and B isto be tested separately as a result of which three comb structures areneeded. Unfortunately each side of the display panel 2 can onlyaccommodate one comb structure.

In FIGS. 5A-D various embodiments of test structures are displayedwherein various aspects of the manufacturing of crossovers according tothe invention have been applied. In general the method of definingcrossovers according to the invention allows one single side of thedisplay panel 2 to accommodate multiple comb structures 21, 22.

In FIGS. 5A and B two embodiments of comb structures for testing amonochrome split display panel 2 are displayed. In both embodiments, atest structure 23 comprises two comb structures, applied on one side ofthe display panel 2.

In FIG. 5A first connecting lines 4 and 4′ and second connecting lines 5and 5′ are applied on the substrate. Next the insulating layer 15 isdeposited on or over the connecting lines 4, 4′, 5 and 5′. Openings 16are created or defined either before or after deposition of theinsulating layer 15 so as to enable connection of the first connectinglines 4′ to the second connecting lines 5′ afterwards. To establish thisconnection the electrically conductive layer 18 is deposited in the areaindicated by 24. The test structure 23 enables the electrodes 8 and 8′,each belonging to a different display panel 2 of the split display, tobe approached and connected to simultaneously from one side of thedisplay panel.

Alternatively, the second connecting lines 5 and 5′ are applied at adifferent stage of the process and the insulating layer 15 is depositedaccordingly, as shown in FIG. 5B.

For colour display panels 2, a test structure 25 comprising three combstructures per panel side may be required, as explained above. In FIGS.5C and 5D, two embodiments of such a test structure 25 are displayed.

The display panel 2 comprises three alternating sets of electrodes 11,11′ and 11″. First connecting lines 4, 4′ and 4″ are applied forconnecting to said sets of electrodes as well as a second connectingline 5. Next, the insulating layer 15 is deposited on or over theconnecting lines 4, 4′, 4″ and 5 and openings 16 are created or definedin order to enable connection to the first connecting lines 4′ and 4″afterwards. Finally the electrically conductive layer 18 is applied inthe areas indicated by 26, which may be separated by applying a shadowmask.

In FIG. 5D a test structure 25 is shown wherein the electricallyinsulating structures 17 are used to separate the connections to be madeto the first connecting lines 4′ and 4″, respectively, if theelectrically conducting layer 18 is applied. Such a test structure 25can be made very compact as the openings 16 can be created more closelyto each other by using the structures 17, which is in contrast to theprocess using shadow masks as displayed in FIG. 5C. The structures 17can be applied at various stages of the process described for the teststructure of FIG. 5C. Preferably however the structures 17 are appliedafter deposition of the insulating layer 15.

In summary, the invention relates to the use of electrically insulatingstructures to define crossovers of connecting lines, which are to bebridged. At the crossover the connecting lines are covered with ainsulating layer in which openings or contact holes are formed. Theelectrically insulating structures are preferably deposited on or overthis insulating layer. Preferably an electrically insulating structureis used for each crossover to minimize the risk of a short-circuitbetween adjacent connecting lines. The electrically insulatingstructures can be aligned very accurately, and in using thesestructures, the standard cathode-making process can be applied to makesmall connecting lines close to each other. The invention allows newtesting and routing methods, and efficient lead-outs for electricaldevices. Such an electrical device may be an organic light emittingdiode or a poly-LED.

For the purpose of teaching the invention, preferred embodiments of theelectrical device, the method of manufacturing a crossover, the teststructure and the method of testing have been described above. It willbe apparent to the person skilled in the art that other alternative andequivalent embodiments of the invention can be conceived and reduced topractice without departing from the true spirit of the invention.

1. A method for manufacturing an electrical device comprising acrossover of at least a first connecting line over at least a secondconnecting line, at least one of said connecting lines connecting to anelectrical device, the method comprising: forming said first connectingline and said second connecting line on a substrate; depositing aninsulating layer on said first connecting line and said secondconnecting line, at least in an area where said crossover is to beformed; creating an opening in said insulating layer in a position wherean electrical contact is to be provided between said first connectingline and a connection point; forming an electrically insulatingstructure peripherally surrounding at least a portion of the area wheresaid crossover is to be formed; and depositing an electricallyconductive layer on the insulating layer to connect said firstconnecting line to said connecting point, which connecting point may beconnected to another second connecting line.
 2. The method of claim 1,wherein said electrically insulating structure is formed so as to extendin a direction substantially perpendicular to said substrate and tocomprise at least one overhanging portion projecting in a directionsubstantially parallel to the surface of said substrate.
 3. The methodof claim 1, wherein said electrically insulating structure surrounds thecrossover.
 4. The method of claim 1, wherein said electrical device isan electroluminescent display device having at least one display pixelcomprising a first electrode, an electroluminescent material and asecond electrode, said method further comprising: forming said firstelectrode simultaneously with said first connecting line and said secondconnecting line; forming an electroluminescent layer on said firstelectrode, at least at a position where the at least one display pixelis to be formed; and forming said second electrode simultaneously withsaid electrically conductive layer, at least at the position where saiddisplay pixel is to be formed, so as to connect said first or secondelectrode with said first connecting line.
 5. The method of claim 4,further comprising: forming said electroluminescent layer after formingsaid electrically insulating structure.
 6. The method of claim 1,wherein said electrical device is an integrated circuit and said firstconnecting line is connected to said integrated circuit.
 7. The methodof claim 6, wherein said integrated circuit is made on a glasssubstrate.
 8. The method of claim 1, wherein the first and secondconnecting lines are formed simultaneously.
 9. The method of claim 1,wherein the first and second connecting lines are formed successively.